Most of the currently available hybrid vehicles have a structure in which a large, box-shaped case of the inverter is fixed on the chassis, and a motor case (trans axle) is arranged therebelow. Considering a driving apparatus for a hybrid vehicle that can be mounted on as wide a variety of models as possible, a structure having two cases is disadvantageous in component standardization, as the arrangements must be optimized model by model.
In principle, it is desirable to put units that require combined operation into one case for integration. In view of the foregoing, Japanese Patent Laying-Open Nos. 2004-343845 and 2001-119961 disclose drive units for a hybrid vehicle in which motors and inverters are integrated.
The driving units for a hybrid vehicle disclosed in Japanese Patent Laying-Open Nos. 2004-343845 and 2001-119961, however, have a structure in which the inverter is simply put on the motor, and there is room for improvement as to the position of center of gravity of the vehicle in the vertical direction, when the structure is installed in the vehicle. Further, reduction in space for mounting the driving unit of the hybrid vehicle is not sufficiently considered.
In order to enable installation to wide variety of models, it is desired that the inverter and the motor are arranged in comparable contour as an automatic transmission generally arranged next to an engine in an ordinary vehicle.
Recently, vehicles having a converter for boosting a battery voltage to attain higher efficiency have been developed. Prior art documents mentioned above are silent about the concept of integrating the inverter and the motor in consideration of integration of the boost converter. When the boost converter is to be integrated, sufficient consideration must be given to the heat generated at the boost converter portion. Particularly for a reactor, which is a large component, some measures for cooling must be provided.